Federal aviation authorities said Tuesday they are investigating claims by a Boeing engineer that the aircraft maker knew of safety flaws in its 787 Dreamliner plane but covered them up to speed production.

The Federal Aviation Administration confirmed the investigation of allegations outlined in articles on Tuesday by The New York Times and The Wall Street Journal describing charges by the whistleblower, who has been at Boeing more than 10 years.

Sam Salehpour, who worked on the Dreamliner, said there were "shortcuts" in Boeing's assembly processes leading to excessively large gaps between different plane parts that could "ultimately cause a premature fatigue failure without any warning, thus creating unsafe conditions for the aircraft with potentially catastrophic accidents", according to an FAA complaint released by Salehpour's attorneys and published by the Journal.

A lawyer for Salehpour told the Times that the FAA had interviewed him on Friday.

Reuters reported that Salehpour's lawyers wrote to the FAA's head, Michael Whitaker, in January stating that Salehpour had made observations working on the 787 manufacturing line in 2021.

Boeing released a statement defending the aircraft, saying it is "fully confident" in the Dreamliner. The company said the issues raised by the engineer "have been subject to rigorous engineering examination under FAA oversight".

Boeing said it incorporated "join verification" into production processes after slowing output and halting deliveries for nearly two years in response to employees who identified "conformance" issues on the 787.

The company also denied charges it retaliated against the worker.

Another whistleblower, John Barnett, a former Boeing employee who had reportedly raised concerns about the company's production issues, was found dead on March 9 of an apparent suicide, according to authorities in South Carolina, Reuters reported.

Whitaker told the Times that the FAA was taking a hard line against Boeing after the Alaska Airlines episode in January, when there was an in-flight blowout of a large fuselage panel of an Alaskan Airlines 737 MAX 9 aircraft. Pressure on Boeing grew this week when an engine cowling fell from a Southwest Airlines 737-800 jet taking off from Denver airport.

Whitaker didn't address Salehpour's claims against Boeing but told the Times that the company "must commit to real and profound improvements".

"This won't be back to business as usual for Boeing," he said in a statement. "Making foundational change will require a sustained effort from Boeing's leadership, and we are going to hold them accountable every step of the way."

Dave Calhoun, who has been Boeing's CEO for four years, announced last month that he plans to step down at the end of this year.

Also on Tuesday, Boeing said that its airplane deliveries dropped in the first quarter to the lowest number since mid-2021 as the company faces increased scrutiny after a door plug blew out from one of its 737 MAX 9 planes midair in January.

The company handed over 83 planes in the three months ended March 31, most of them 737s, compared with 157 in the prior quarter and 130 planes in the year-earlier period, Reuters reported. In March, Boeing delivered 29 planes. Rival Airbus said Tuesday that it delivered 142 planes in the first three months of the year, 63 of them in March.